JERUSALEM — The call came to the cellphone of his brother’s wife, Salah Kaware said Tuesday. Kaware lives in Khan Younis, in southeast Gaza, and the caller said that everyone in the house must leave within five minutes, because it was going to be bombed.

A further warning came as the occupants were leaving, he said in a telephone interview, when an Israeli drone apparently fired a flare at the roof of the three-story home. “Our neighbors came in to form a human shield,” he said, with some even going to the roof to try to prevent a bombing. Others were in the stairway when the house was bombed not long afterward.

Seven people died, Kaware said, a figure also stated by the Palestinian Health Ministry in Gaza, which also said that 25 people were wounded. The Israeli military said that targeted houses belonged to Hamas members involved in launching rockets or other military activity, and that they had been used as operations rooms.

But the events Tuesday were another example of a contentious Israeli policy in which occupants of a building about to be bombed or shelled are given a brief warning in Arabic to evacuate. The Israelis have used such telephone calls and leaflets for years now, in a stated effort to reduce civilian casualties and avoid charges of indiscriminate killings or even of crimes against the rules of war.

During Operation Cast Lead in Gaza in late 2008, the Israelis often used telephone calls and leaflets to tell occupants to leave before striking. In some cases, the Israelis fired missiles without explosive warheads onto the roof to get Palestinians who had gathered there to leave. The Israelis called it “the knock on the roof.” But often, as in Khan Younis on Tuesday, people die in any case, because they ignore or defy the warnings, or try to leave after it’s too late.

— New York Times News Service

JERUSALEM — Israel and Hamas escalated their military confrontation Tuesday, with Israel carrying out extensive air attacks in response to heavy rocket fire and authorizing a major call-up of army reserves for an extended campaign against militants in Gaza.

Late Tuesday, Hamas took responsibility for the launch of a new wave of as many as 40 longer-range rockets, some of them intercepted over Tel Aviv and even Jerusalem, where sirens sounded around 10 p.m. There were no reports of injuries, but the barrage of rockets, one of which hit an open area in outer Jerusalem, put pressure on the Israeli government to respond with greater force.

Israel warns Gaza targets, though people still die

JERUSALEM — The call came to the cellphone of his brother’s wife, Salah Kaware said Tuesday. Kaware lives in Khan Younis, in southeast Gaza, and the caller said that everyone in the house must leave within five minutes, because it was going to be bombed.

A further warning came as the occupants were leaving, he said in a telephone interview, when an Israeli drone apparently fired a flare at the roof of the three-story home. “Our neighbors came in to form a human shield,” he said, with some even going to the roof to try to prevent a bombing. Others were in the stairway when the house was bombed not long afterward.

Seven people died, Kaware said, a figure also stated by the Palestinian Health Ministry in Gaza, which also said that 25 people were wounded. The Israeli military said that targeted houses belonged to Hamas members involved in launching rockets or other military activity, and that they had been used as operations rooms.

But the events Tuesday were another example of a contentious Israeli policy in which occupants of a building about to be bombed or shelled are given a brief warning in Arabic to evacuate. The Israelis have used such telephone calls and leaflets for years now, in a stated effort to reduce civilian casualties and avoid charges of indiscriminate killings or even of crimes against the rules of war.

During Operation Cast Lead in Gaza in late 2008, the Israelis often used telephone calls and leaflets to tell occupants to leave before striking. In some cases, the Israelis fired missiles without explosive warheads onto the roof to get Palestinians who had gathered there to leave. The Israelis called it “the knock on the roof.” But often, as in Khan Younis on Tuesday, people die in any case, because they ignore or defy the warnings, or try to leave after it’s too late.

He said he was prepared to “remove the gloves” and undertake the third major military offensive in five years against militants in the Hamas-controlled territory if rocket attacks from Gaza did not cease.

Both sides resorted to a show of military strength after a series of quick-fire events that illustrated the extreme fragility of Israeli-Palestinian relations. They included the collapse of U.S.-sponsored peace talks, the attempts by rival Palestinian factions to form a coalition government, the kidnapping and murder of three Israeli teenagers and a revenge kidnapping and murder of a Palestinian teenager.

Palestinian officials said at least 23 people were killed Tuesday in Gaza, where repeated bombardments shook buildings and sent thousands of people into the streets. Israeli officials said two people in Israel were wounded by rocket attacks Monday.

As the rockets and jet fighters flew, Israeli officials emphasized that their goal was to restore quiet to southern Israel, where many thousands of Israelis fled to shelters and schools were shut. But Netanyahu’s government was also under pressure for a more extensive operation, including ground troops, to destroy a military infrastructure in Gaza rebuilt since Israel’s last campaign there in 2012.

At the same time, Hamas needed to show more radical groups in Gaza that it could stand up to Israel. It has been weakened by the installation of an antagonistic military-backed government in Egypt, which has moved to seal the border with Gaza, sharply reducing Hamas’ tax receipts. Hamas has little to show for its coalition with Fatah and appears to have fallen back on its main principle of armed resistance to Israel.

This latest confrontation has roots in the kidnapping and murder last month of the three Israeli teenagers by men in the West Bank who Israel alleges belong to Hamas, followed by the kidnapping and murder of the Palestinian teenager, reportedly by members of an anti-Arab group of supporters of the Beitar Jerusalem soccer team known as La Familia. Micky Rosenfeld, the Israeli police spokesman, and a lawyer for two of the suspects said that they did not know if that was true and that the investigation was continuing.

The kidnapping and murder of the Israeli teenagers led to an extensive crackdown by Israeli troops on Hamas in the West Bank, which in turn appeared to push Hamas to respond from Gaza, which it controls.

As both sides tried to send political messages through military activity, the Israeli military said earlier Tuesday night that more than 150 rockets had been fired at Israel, of which at least 29 were intercepted. Israel hit some 150 targets, the military said, including five senior Hamas officials, 10 smuggling tunnels, 90 concealed rocket launchers and 18 weapon storage and manufacturing sites. One of those killed was reportedly Muhammad Shaban, a senior Hamas military officer, when a missile hit his car.

The Palestinian authorities in Gaza said at least two teenagers were among the dead from Israeli air attacks on targets that included the car and homes of Hamas members and officials. Seven died in one house in Khan Younis, bombed after a telephoned warning.

Ashraf al-Qedra, a Health Ministry spokesman, said more than 100 people had been wounded in the aerial assaults. President Mahmoud Abbas of the Palestinian Authority, who has condemned the murders of the Israeli teens, demanded that Israel immediately stop.

Tuesday evening, the Israeli army said, with little detail, that it had defeated an effort to attack an army base in southern Israel by “several gunmen armed with grenades” who had approached from the sea.

The justice minister and Israeli negotiator, Tzipi Livni, said that Israel was reluctant to conduct a ground operation, but that one might be necessary. Speaking during a conference on peace organized by the Haaretz newspaper, she said, “It is our duty to provide security to the citizens of Israel, and we need to see what the right way to do this is.”

It is up to Hamas, she said.

“If Hamas does not allow Israelis to live in peace, and then we, too, will be forced to carry out actions that we don’t fundamentally wish to perform, and that are not our primary goal,” she said.